The Interstellar Tool Builders

byPaul GilsteronOctober 19, 2010

Long before I knew what ideas for interstellar flight were out there in the literature, I always saw the idea of a trip between the stars in Homeric terms. It would be an epic journey that, like that of Odysseus, would resonate throughout human history and become the stuff of legend, even myth. In back of all that was the belief that any vehicle we could design that could carry people and not just instruments to the stars would be a ‘generation ship,’ in which the crew were born, raised their families, lived their lives and died while the ship, moving at maybe 1 percent of light speed, pressed on to destination.

That familiar science fiction trope still has a ring of truth about it, because if for some reason we as a species decided we absolutely had to get a few human beings to Alpha Centauri, about the only option we would have for the near-term is a solar sail and a close-pass gravity assist by the Sun, and even in the best case scenario, that still works out to around a thousand year journey. Epic indeed. Now and then I re-read old science fiction tales like Brian Aldiss’ Non-Stop’ (published in the US as Starship) and Robert Heinlein’s Orphans of the Sky to be reminded of how firmly such notions managed to settle into our psyche as the idea of star travel grew. And I think about Odysseus and crew on that wine-dark sea that would almost destroy them.

We’d like to do better, of course, which is why long-shot concepts like Alcubierre’s ‘warp drive’ continue to intrigue us. Igor Smolyaninov, now at the University of Maryland, has been working with metamaterials to study the Alcubierre concept of altering spacetime itself so that a ship could move in a kind of ‘bubble’ that never exceeds the speed of light through space while radically reducing travel times. As Richard Obousy showed us yesterday, Smolyaninov’s interest is in developing the needed tools to study the warping of spacetime in the laboratory.

Metamaterials are the result of engineering that alters how light behaves as it moves through the materials, and Smolyaninov is interested in how they can help us simulate the behavior of light under the kind of extreme gravitational conditions a warp drive would create. I think Richard did a terrific job of showing us that what we are doing here is to simulate exotic light ray trajectories because of the unique properties of metametarials. We are definitely not talking about creating anything beyond a simulation of what happens to spacetime near a sublight warp drive.

What Smolynaninov wants to demonstrate, then, is a tool for the further study of these ideas, and I leave it to those better qualified than myself to judge the quality of his findings. Warp drive is a fantastically problematic concept, one that demands exotic matter with negative energy density, and one that suffers from instability from quantum effects and may well be prohibited by the laws of physics, as Smolyaninov is quick to point out. Nonetheless, he adds:

…our results demonstrate that physics of a gradually accelerating warp drive can be modeled with newly developed “perfect” magnetoelectric metamaterials built from split ring resonators. Since even low velocity physics of warp drives is quite interesting, such a lab model deserves further study.

I’m reminded of Claudio Maccone’s continuing work on the Karhunen-Loève Transform (KLT) and the mathematical tools that may one day be needed to communicate with spacecraft moving at relativistic speeds. Yes, we are generations away from such spacecraft (although the KLT techniques Maccone studies have already been used for spacecraft communication with the Galileo mission), but creating the mathematical frameworks and the laboratory experiments to help us study the implications of fast interstellar flight is part of building toward that future.

Also along the lines of fast travel comes news from NASA Ames director Pete Worden that the center has begun a project with DARPA called ‘the Hundred Year Starship.’ Worden made the announcement at a Long Now Foundation event in San Francisco, but went on to spend most of his talk on unrelated near-term ideas like electric propulsion and microwave thermal propulsion, in which power is beamed to a spacecraft and used to heat a propellant, allowing missions to be designed in which the fuel onboard can be reduced, to the benefit of payload size.

The latter ideas have little to do with the ‘Hundred Year Starship,’ but just who is in charge of this project, how NASA and DARPA will develop it, and what its goals are (does it envision a starship that can be launched within a hundred years, or a starship that can complete a hundred-year mission to a star?) remains to be seen. DARPA, according to this account, is putting $1 million into the project, with $100K from NASA. More on this as it becomes available, and here’s to the notion of keeping our enthusiasm for the challenge even at this early stage of building the tools we need to define it. On that score, an occasional dose of science fiction is highly recommended.

Comments on this entry are closed.

EniacOctober 19, 2010, 9:44

About the only option we would have for the near-term is a solar sail and a close-pass gravity assist by the Sun

I disagree. I would like to submit that a) using solar sails in such a way is pure theoretical speculation at this point, and that b) both nuclear-electric ion engines and controlled nuclear detonations are much more practical approaches to reaching 0.01 c in the near-term.

A quick Google search returns little; has anyone ever followed up on the practical application of Heim Theory? As I understand it, a massive, superconducting disk is rapidly rotated (many tens of thousand RPMs) in a strong (50 Tesla+) magnetic field. Funny business occurs, and the disk, with everything attached to it, are conferred a propulsive force. In one configuration this results in high relative velocities. In another, a sort of bubble of space-time appears and your putative INSS MacArthur, never exceeding lightspeed within that S/T bubble, nonetheless arrives at its destination faster than Causality would allow.

I know. Heim Theory is wacky, handwritten, and in an obscure German dialect. But we are talking about FTL, and that is wacky as well.

The truly intriguing part, to me anyway, is the unique quality of Heim Theory; while it is derived from GR, it correctly predicts the rest mass of all particles (within the standard error of measure), something no other theory, from QM to SR, GR, M and all the flavors of String, have done.

This is probably a case of, “there is nothing there, there” but math from GR predicting rest mass of electrons and protons and magneto-gravitinos . . .

The Hundred Year Starship sounds similar to the objectives of Project Longshot: “The journey to Alpha Centauri B orbit would take about 100 years, at an approx. velocity of 13411 km/s, about 4.5% the speed of light…” http://en.wikipedia.org/wiki/Project_Longshot

Is it possible that Project Icarus has inspired new life into official projects? $1.1M isn’t much, but in these tight budget times, government funding from two sources… this is not nothing.

If we do send large ‘Generation’ ships out to other stars it does not necessarily mean that they will take thousands of years to get there, if a new propulsion technolgy is discovered on earth the information to construct it can be transmitted to these ships and the new devices manufactured aboard them.

Clarke’s Rama was an interesting variation of interstellar ark. These vessels were dormant for most of the voyage, activating within a certain distance of the target star. It would also draw raw material during a sundiver maneuver from the sun itself to compensate for inevitable leakage.

To Michael: onboard manufacturing is applicable if there is a surfeit of energy to allow the modification. Also the vessel’s ability to endure additional stresses and head-on encounters with any interstellar media would have to be addressed. With exotic relativistic speeds come higher frequencies (in every sense) of radiation and cosmic rays, and so-called warp schemes are calculated to likely flood the vessel with such radiation.

Michael: Retrofitting propulsion in flight is like asking the crew of the Santa Maria to retrofit a steam engine from blueprints alone while en route to the new world. Utterly undoable on so many levels….

Somewhat more likely is an evacuation mission, but that, too, is unlikely because the extra stop and start to pick up the poor saps is going to be impractical with anything but the most fantastically advanced technology.

I am afraid the only decision to be made in this situation is whether to tell them or not….

I still think that, given expected development in nanotechnology, the most likely “manned” interstellar voyage is one in which some form of solar-based energy-carrying beam (possibly a huge laser or maser beam, but possibly also a stream of relativistic solid projectiles) accelerates a multistage lightsail (or other momentum-capturing device) to say three to ten percent of lightspeed, with the second stage used to decelerate to near-zero velocity at the destination (see Robert Forward for examples).

Once there, the payload would use local resources and store information to replicate human (and other?) embryos, bring them to term and with humaniform robots, raising them to adulthood.

Yes, I know this sounds difficult — but surely it’s much easier than building a (vastly larger) human-rated interstellar craft with the numbers of human passengers that would be desired if an entire stellar system were to be colonised.

One thing that often crops up in these novels is that having lived for generations in a stable habitable starship the nth generation crew arrive at the destination with little enthusiam for abandoning it in favour of new world. If FTL or even significant (10% plus I’m thinking) fractions of c do turn out to be impractical, then we may go to the stars not as colonists, but as nomads, seing star systems only as interesting places to stop and re-supply. So if the issue of highly advanced FTL ships overtaking the STL ships ever comes up, the STL crews may just go ‘meh..’!

The SF colonising the stars scenario I like is the one in which huge space settlement orbiting the Sun simply decide to replace endlessly going around in circles with endless linear movement through space, no big deal for them as they would be taking everything and everyone important to them with them.

@Carl Keller: something intermediate can be found in Clarke’s ‘Songs of Distant Earth’, in which the passengers are kept in some kind of hibernation/suspended animation condition for many decades on their ways to their stellar destinations.

@John Freeman: no, I am afraid that the nomad/asteroid/Oort cloud object/Kuiper belt object/etc. idea won’t work in the long run, as I have argued several times, for very fundamental stochastic (statistical) reasons of chance event extinction, similar to the principles of island biogeography: small islands run very high risks of disastrous chance events, resulting in total wipe out.
In simple terms: s..t happens and the smaller the island, the greater the chance per time unit of this happening. In fact the chance of a total disaster increases exponentially with decreasing island size.

This is the main reason why large organisms and species rich ecosystems can mainly persist on continents and not on small remote islands.

Likewise, the chance of a total distaster happening to a small asteroid sized colony during a couple of centuries must be huge. Think of epidemics, failure of vital life support systems, simply running out of vital resources, conflict, accidents (both internal and external), …

Inversely, a growing population of more or less independent habitats (e.g. dome settlements) on a terraformable planet (such as Mars) will run a decreasing chance of total extinction as time proceeds.

We will need to minimize exposure time to space (i.e. travel time) and maximize our habitation time of planets.

I wonder if something like metamaterials could be used as shielding, to divert particles away from the ship. Particles entering the material would veer off at an angle and miss the ship. I don’t know how well that would work for asteroid-sized objects.

It doesn’t matter how long the trip takes if the ship is automated and carries only frozen humans, embroyos, or just eggs and sperms. Ten thousand years might pass in ‘timeless’ stasis. Thaw them out some years before arrival , and then let them grow up with HAL2000 for a Mom. It’s heartless, but it may be easier to develop that technology than to develop FTL tech . And the colonists may be psychologically ‘alien’ from us old stock humans, even if they do get established some where. They’ll have to compromise with their new realities. Sink or swim.
Even more heartless, we could send a thousand of these automated , one-way colonial ships, and know full well that only 1% will succeed. God help Earth if they someday come back at us, ‘demented’ and ‘alien’ in their thinking.

In the Echoes of Earth trilogy a 1000 copies of software emulations are sent to nearby stars. They develop the means to produce android bodies for exploration at their destination so they’re in adult bodies rather than being children. The novels turn into first contact stories with an interesting twist in short order, but the initial exploration program by Earth is interesting. Turns out the software people are unstable and eventually breakdown due to being disembodied.

@Stephen: Metamaterials work the way they do for light because their constitutents (the atoms) are much smaller than the wavelength of light. When hit by fast moving particles (nuclei, protons, electrons, muons, even gamma rays), they will scatter like any other material. Randomly, that is, in accordance with Rutherford’s experiment. Plus, if the energy is high enough, there will be nuclear reactions with even less predictable outcomes.

Retrofitting propulsion in flight is like asking the crew of the Santa Maria to retrofit a steam engine from blueprints alone while en route to the new world. Utterly undoable on so many levels….

If the generation ship had a surfeit of untapped raw materials on board it might be possible. If for example it was made of a partially hollowed-out asteroid like in some proposed ideas. But of course that supposes that the original engineers planned for or anticipated this sort of thing and left these resources in situ, which otherwise would just be inconvenient excess mass that would probably be jettisoned somewhere in the construction stages before launch.

That said, any generation ship design is going to have to possess self repair capability, just to account for time-based attrition. So incremental improvements to their drive system ought not be inconceivable. A complete overhaul/replacement to a revolutionary new system of course is something else entirely.

@Stephen
“Retrofitting propulsion in flight: There might be plenty of interstellar comets to provide raw materials, so the generation ships wouldn’t have to take all that raw material along for the whole trip…?”

Are you suggesting the ship decelerate, pick up the comet, and then accelerate back to .1C?

A generation ship would be a world in itself, it’ll have a functioning economy with all the art, science, manufacturing and engineering facilities a similar sized nation in the solar system would have, it has to be that way because it has the be able to sustain itself for huge periods of time on its voyage and then utilise the raw materials it finds at its destination, so it has either carry spacecraft or have the ability to manufacture them, the latter makes more sense, as when they get used at the destination they’ll wear out and need replacing.

It will of course maintain contact with the solar system, and it’ll incorporate the technology developed in the solar system into its own systems, this would be anticipated from the outset.

Ride a starship? Not for a century
Alan Boyle writes: It turns out that the $1.1 million “Hundred Year Starship” project is a yearlong study for a multigenerational mission which is yet to be named … and for which humans might need to be re-engineered.

Pete Worden, director of NASA’s Ames Research Center, created a stir last month at a conference sponsored by the Long Now Foundation when he mentioned that the space agency was kicking in an extra $100,000 to the project, sponsored by the Pentagon’s Defense Advanced Research Projects Agency. (You can hear him talk about it in the video referenced above.) Worden also said he was trying to get billionaires to form a starship fund.

In an Oct. 28 news release, DARPA explained that the actual interstellar journey was a long, loooong way from taking off.

In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For the last eleven years, this site has coordinated its efforts with the Tau Zero Foundation, and now serves as the Foundation's news forum. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image: Marco Lorenzi).

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